In agricultural equipment such as irrigation systems, power mowers and the like, power is typically transferred through a gearbox from a power source, such as a motor or the PTO of a tractor, to the equipment. Typically, the drive motors or power input device has a round output shaft that is coupled to a square drive shaft of the gearbox of the equipment. In the agricultural industry, these square in-line drive shafts generally range from ¾″ to 1″ square.
As with other components of agricultural equipment, the couplers utilized to inter-connect the square drive shaft with the round output shaft are often subject to extreme operating conditions and environments. For example, common in such environments are hazards such as moisture, corrosive liquids including liquidized manure, the full range of soil and mineral conditions, insects and temperature extremes which could range from continental polar to equatorial. Likewise, because the terrain on which agricultural irrigation systems operate is often rocky, uneven and has varying surface conditions, such couplers are subject to high torque.
The standard prior art coupler consists of a rubber dampening puck sandwiched between two, two-piece collars. The dampening puck absorbs shock that could be transferred between the two collars and permits a degree of flexibility between the interconnected drive shafts. One collar, and in particular, the two mating halves of the collar, are disposed to fit around the round cross-section end of the output shaft of the drive motor while the other collar, and in particular, the two mating halves of the collar, are disposed to fit around the square cross-sectioned end of the input shaft. Each collar typically has one or more flanges that permit it to be bolted or attached to the flange of the other collar, with the dampening puck disposed between the adjacent flanges. Likewise, each collar half is disposed to engage the other collar half and secure to one another around the shaft utilizing standard fasteners, so that each collar has a compression fit around the shaft over which it is disposed. As mentioned above, the dampening puck is generally formed of rubber or other shock absorbing material such as polyurethane. The collars are generally formed of aluminum or similar metal cast to fit the specific drive shaft size and shape.
One drawback to these prior art couplers is that they have significant manufacturing costs, in that each collar half must be cast or otherwise formed and machined to the specifications of the particular coupling. Further, in order to provide a coupling that is sufficiently sturdy and rugged for the agricultural industry, the metal collar components typically require a comparatively large amount of material to form the collar sections.
Another drawback to the foregoing prior art coupling devices is that the fasteners clamping the two halves of a collar around a shaft may become loose over time, particularly under the vibrations of use, permitting the shaft to spin freely within the coupling. Not only could this result in a loss of power, but could also result in damage to the coupling, shafts, or equipment. Moreover, if the two halves were to completely separate, they could cause harm to nearby persons or equipment.
Thus, it would be desirable to provide a coupling with reduced manufacturing costs but with enhanced coupling ability.